A repunched mintmark on a 1956 D Washington Quarter that is listed only one other website found by me, John Wexler's Coins & Die Varieties. HIs designation; 1956 D 25¢ WRPM-004 and his description "D/D Tilted (Rotated).
Markers include; Obverse - Light E/W die scratch inside the lower hole of the B in LIBERTY. Reverse - Weak E/W die scratches inside the upper area of the second R in QUARTER.
I have added photos of these markers here and added one I  believe is of value and that is a horizontal die scratch in the upper portion of the letter E in UNITED on the reverse. It does have split serifs but the daramatic step quality south and east has a mechanical look.
The coin is in excellent uncirculated condition with very, very light toning around the rim. A 1956 would also be 90% silver.